Tungsten for wordline applications

ABSTRACT

Disclosed herein are methods and related apparatus for formation of tungsten wordlines in memory devices. Also disclosed herein are methods and related apparatus for deposition of fluorine-free tungsten (FFW). According to various embodiments, the methods involve deposition of multi-component tungsten films using tungsten chloride (WCl x ) precursors and boron (B)-containing, silicon (Si)-containing or germanium (Ge)-containing reducing agents.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 62/115,012, titled “TUNGSTEN FOR WORDLINE APPLICATIONS,” filed Feb. 11, 2015, all of which is incorporated herein by reference in its entirety and for all purposes.

BACKGROUND

Tungsten (W) film deposition using chemical vapor deposition (CVD) techniques is an integral part of semiconductor fabrication processes. For example, tungsten films may be used as low resistivity electrical connections in the form of horizontal interconnects, vias between adjacent metal layers, and contacts between a first metal layer and the devices on a silicon substrate. In an example tungsten deposition process, a barrier layer is deposited on a dielectric substrate, followed by deposition of a thin nucleation layer of tungsten film. Thereafter, the remainder of the tungsten film is deposited on the nucleation layer as a bulk layer. Conventionally, the tungsten bulk layer is formed by the reduction of tungsten hexafluoride (WF₆) with hydrogen (H₂) in a chemical vapor deposition process.

Tungsten films may also be used in various memory applications, including in formation of buried wordline (bWL) architectures for dynamic random access memory (DRAM). In an example of bWL deposition, a tungsten layer may be deposited on a titanium nitride (TiN) layer to form a TiN/W bilayer by a CVD process using WF₆.

SUMMARY

Disclosed herein are methods of depositing tungsten on a substrate. In some embodiments, the methods include pulsing a reducing agent, wherein the reducing agent is boron (B)-containing, silicon (Si)-containing or germanium (Ge)-containing and pulsing a tungsten chloride precursor, wherein the tungsten chloride precursor is reduced by the reducing agent or a product thereof to form a multi-component tungsten-containing film containing one or more of B, Si, and Ge on the substrate.

In some embodiments the methods involve pulsing a third reactant to form a ternary tungsten-containing film. The third reactant may be a nitrogen-containing or carbon-containing reactant such that the ternary tungsten-containing film includes tungsten, one of silicon, germanium, and boron, and one or carbon and nitrogen. Quaternary and higher order films containing two or more of silicon, germanium, boron, carbon, and nitrogen may be formed. In some embodiments, the multi-component film is a binary film.

In some embodiments, the multi-component tungsten-containing film is a diffusion barrier for a wordline. In some embodiments, the multi-component tungsten-containing film is a work function layer for a metal gate.

In some embodiments, the substrate temperature during the tungsten chloride pulse is at least 400° C. In some embodiments, the substrate temperature during the tungsten chloride pulse is at least 450° C. In some embodiments, the substrate temperature during the tungsten chloride pulse is at least 500° C. In some embodiments, the substrate temperature during the tungsten chloride pulse is at least 550° C.

In some embodiments, the substrate temperature during the tungsten chloride and reducing agent pulses is at least 400° C. In some embodiments, the substrate temperature during the tungsten chloride and reducing agent pulses is at least 450° C. In some embodiments, the substrate temperature during the tungsten chloride and reducing agent pulses is at least 500° C. In some embodiments, the substrate temperature during the tungsten chloride and reducing agent pulses is at least 550° C.

The method may further include depositing a bulk tungsten (W) layer on the multi-component tungsten-containing film. In some embodiments, the bulk W layer is deposited by a chemical vapor deposition (CVD) reaction between a tungsten chloride precursor and a reducing agent.

The bulk layer may be deposited directly on the multi-component tungsten-containing film without an intervening layer in some embodiments.

According to various embodiments, the multi-component tungsten-containing film is deposited directly on an insulating film, such as an oxide or nitride film. In some embodiments, the method involves decomposition of the reducing agent to form a layer of B, Si, or Ge on the substrate.

Also provided are memory structures. In some embodiments, a memory structure may include a liner layer of a multi-component tungsten-containing film containing one or more of B, Si, and Ge; and a tungsten wordline. In some embodiments, a memory structure may include a work function layer of a multi-component tungsten-containing film containing one or more of B, Si, and Ge; and a metal gate.

These and other aspects are described further below with reference to the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic example of a dynamic random access memory (DRAM) architecture including a buried wordline (bWL) in a silicon substrate.

FIG. 2A depicts a schematic example of a three-dimensional NAND structure including tungsten wordlines.

FIG. 2B is a two-dimensional rendering of three-dimensional features of a partially-fabricated 3D NAND structure including a tungsten wordline.

FIG. 2C shows a schematic example of a vertical NAND structure including a tungsten-containing work function layer.

FIG. 3A shows an example of a method that may be used to form a tungsten-containing binary or ternary film.

FIG. 3B shows an example of a method that may be used to fill a feature.

FIG. 4 is a block diagram of a processing system suitable for conducting tungsten deposition processes in accordance with embodiments of the invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

Semiconductor device fabrication often involves the deposition of tungsten films, for example in trenches or vias to form interconnects. In a conventional methods of depositing tungsten films, a nucleation tungsten layer is first deposited into a via or contact. In general, a nucleation layer is a thin conformal layer that serves to facilitate the subsequent formation of a bulk material thereon. The tungsten nucleation layer may be deposited to conformally coat the sidewalls and bottom of the feature. Conforming to the underlying feature bottom and sidewalls can be critical to support high quality deposition. Nucleation layers are often deposited using atomic layer deposition (ALD) or pulsed nucleation layer (PNL) methods.

In a PNL technique, pulses of reactant are sequentially injected and purged from the reaction chamber, typically by a pulse of a purge gas between reactants. A first reactant can be adsorbed onto the substrate, available to react with the next reactant. The process is repeated in a cyclical fashion until the desired thickness is achieved. PNL is similar to ALD techniques. PNL is generally distinguished from ALD by its higher operating pressure range (greater than 1 Torr) and its higher growth rate per cycle (greater than 1 monolayer film growth per cycle). Chamber pressure during PNL deposition may range from about 1 Torr to about 400 Torr. In the context of the description provided herein, PNL broadly embodies any cyclical process of sequentially adding reactants for reaction on a semiconductor substrate. Thus, the concept embodies techniques conventionally referred to as ALD. In the context of the disclosed embodiments, CVD embodies processes in which reactants are together introduced to a reactor for a vapor-phase reaction. PNL and ALD processes are distinct from CVD processes and vice versa.

After the tungsten nucleation layer is deposited, bulk tungsten is typically deposited by a chemical vapor deposition (CVD) process by reducing tungsten hexafluoride (WF₆) using a reducing agent such as hydrogen (H₂).

Conventional deposition of tungsten has involved the use of the fluorine-containing precursor WF₆. However, the use of WF₆ results in some incorporation of fluorine into the deposited tungsten film. As devices shrink, features become smaller and the detrimental effects electromigration as well as ion diffusion become more prominent, thereby causing device failure. The presence of fluorine can cause electromigration and/or fluorine diffusion into adjacent components, thereby reducing the performance of the device. Tungsten films containing traces of fluorine can thereby pose integration and reliability issues, as well as device performance issues related to the underlying films.

Disclosed herein are methods and related apparatus for formation of tungsten wordlines in memory devices. Also disclosed herein are methods and related apparatus for deposition of fluorine-free tungsten (FFW). FIG. 1 depicts a schematic example of a DRAM architecture including a buried wordline (bWL) 11 in a silicon substrate 9. The bWL is formed in a trench etched in the silicon substrate 9. Lining the trench is a conformal barrier layer 12 and an insulating layer 13 that is disposed between the conformal barrier layer 12 and the silicon substrate 9. In the example of FIG. 1, the insulating layer 13 may be a gate oxide layer, formed from a high-k dielectric material such as a silicon oxide or silicon nitride material.

In some embodiments disclosed herein the conformal barrier layer 12 is a tungsten-containing layer. In conventional tungsten (W) wordline architectures, titanium nitride (TiN) is used as a barrier. However, TiN/W wordline fill is limited by the resistivity scaling; because TiN has relatively high resistivity, as dimensions decrease and TiN conformal layers occupy a greater volume fraction of the trench, the resistance increases. According to various embodiments, the tungsten bWLs disclosed herein are free of TiN and other non-W barrier layers.

The conformal barrier layer 12 may include one or more of boron, silicon, and germanium. In some embodiments, the conformal barrier layer 12 is a binary compound such as WB_(x), WSi_(x), and WGe_(x), where x is a number greater than zero. In some embodiments, the conformal barrier layer 12 may include carbon or nitrogen. In some embodiments, the conformal barrier layer 12 may include one or more of boron, silicon, and germanium, and one or both of carbon and nitride. In some embodiments, the conformal barrier layer 12 is a ternary compound such as WB_(x)N_(y), WSi_(x)N_(y), WGe_(x)N_(y), WSi_(x)C_(y), WB_(x)C_(y), WGe_(x)C_(y), etc., wherein x and y are numbers greater than zero. Quaternary and higher order compounds containing Si, B, Ge, N and C may also be used, with examples including WB_(x)Ge_(y)N_(z), WGe_(x)C_(y)N_(z), etc. wherein x, y and z are numbers greater than zero.

FIG. 2A depicts a schematic example of a wordline 21 in a 3D NAND structure 23. In FIG. 2B, a 2-D rendering of 3-D features of a partially-fabricated 3D NAND structure after tungsten fill, is shown including the wordline 21 and a conformal barrier layer 22. FIG. 2B is a cross-sectional depiction of a filled area with the pillar constrictions 24 shown in the figure representing constrictions that would be seen in a plan rather than cross-sectional view. The conformal barrier layer 22 may be a tungsten-containing layer as described above with respect to the conformal barrier layer 12 in FIG. 1. The tungsten-containing film may serve as a barrier layer and a nucleation layer for subsequent CVD W deposition.

In some embodiments, a tungsten-containing work function layer for a metal gate is provided, including a work function layer for a metal gate in a 3-D memory structure such as the 3-D NAND structure above.

FIG. 2C shows a schematic example of a VNAND structure 32 including metal gates 31 formed on a substrate 30, with an enlarged view of an example of a metal gate 31 and associated film stack also shown. The VNAND structure 32 includes a semiconducting channel 33, a tunnel dielectric layer 35, a charge storage layer 37, a work function layer 39, a blocking dielectric 41, and a metal gate 31.

Examples of work function layers in memory structures including those shown in the examples of FIGS. 2A-2C include films of a binary tungsten-containing compound such as WB_(x), WSi_(x), and WGe_(x), where x is a number greater than zero. In some embodiments, the work function layer may include carbon or nitrogen. In some embodiments, the work function layer may include one or more of boron, silicon, and germanium, and one or both of carbon and nitride. In some embodiments, the work function layer is a ternary compound such as WB_(x)N_(y), WSi_(x)N_(y), WGe_(x)N_(y), WSi_(x)C_(y), WB_(x)C_(y), WGe_(x)C_(y), etc. Quaternary and higher order compounds containing Si, B, Ge, N and C may also be used. The tungsten-containing film may serve as a work function layer and a nucleation layer for subsequent CVD W deposition. The work function layer may be deposited on a dielectric material such as a gate oxide.

In some embodiments, the memory structures described with reference to FIGS. 2A-2C do not include TiN diffusion barriers or TiN work function layers.

FIG. 3A shows an example of a method that may be used to form a tungsten-containing binary or ternary film. First, a substrate is exposed to a reducing agent pulse (302). The substrate may be a partially-fabricated memory device in some embodiments. In some embodiments, a surface that is exposed to the reducing agent pulse on which the film is formed is a dielectric. According to various embodiments, the film may be formed on other types of surfaces including conducting and semiconducting surfaces.

The reducing agent employed in block 302 will reduce a tungsten-containing precursor employed in a subsequent operation as well as provide a compound to be incorporated into the resulting film. Examples of such reducing agents include boron-containing, silicon-containing, and germanium-containing reducing agents. Examples of boron-containing reducing agents include boranes such B_(n)H_(n+4), B_(n)H_(n+8), B_(n)H_(m), where n is an integer from 1 to 10, and m is a different integer than m. In particular examples, diborane may be employed. Other boron-containing compounds may also be used, e.g., alkyl boranes, alkyl boron, aminoboranes (CH₃)₂NB(CH₂)₂, and carboranes such as C₂B_(n)H_(n+2). Examples of silicon-containing compounds include silanes such as SiH₄ and Si₂H₆. Examples of germanium-containing compounds include germanes, such as Ge_(n)H_(n+4), Ge_(n)H_(n+6), Ge_(n)H_(n+8), and Ge_(n)H_(m), where n is an integer from 1 to 10, and n is a different integer than m. Other germanium-containing compounds may also be used, e.g., alkyl germanes, alkyl germanium, aminogermanes and carbogermanes.

According to various embodiments, block 302 may involve adsorption of a thin layer of thermally decomposed elemental boron, silicon or germanium onto the surface of the substrate. In some embodiments, block 302 may involve adsorption of a precursor molecule onto substrate surface.

Next, the chamber in which the substrate sits may be optionally purged (304). A purge pulse or an evacuation can be employed to remove any byproduct, if present, and unadsorbed precursor. This is followed by a pulse of a tungsten chloride precursor (306). Tungsten chloride precursors include WCl₂, WCl₄, WCl₅ and WCl₆, as well as mixtures of these. In some embodiments, the tungsten chloride precursor is tungsten hexachloride (WCl₆), tungsten pentachloride (WCl₅) or a mixture thereof. An optional purge (307) may be performed after block 306 as well. The tungsten precursor is reduced by the reducing agent (or a decomposition or reaction product thereof) to form the multi-component film.

A deposition cycle will typically deposit a portion of the tungsten-containing layer. After block 307, a deposition cycle may be complete in some implementations with the deposited film being a tungsten-containing binary film such as WB_(x), WSi_(x), and WGe_(x), where x is greater than zero. In such embodiments, the process may proceed to block 312 with repeating the cycle of blocks 302-307 until the desired thickness is deposited. Example growth rates may be about 100 Å per cycle.

In some embodiments, the process will proceed with optionally introducing a third reactant (308). The third reactant will generally contain an element to be introduced into the film, such as carbon or nitrogen. Examples of nitrogen-containing reactants include N₂, NH₃, and N₂H₄. Examples of carbon-containing reactants include CH₄ and C₂H₂. An optional purge (309) may follow. The process may then proceed to block 312 with repeating the deposition cycle.

Examples of ternary films including nitrogen or carbon are given above. In some embodiments, a film may include both nitrogen and carbon (e.g., WSiCN).

According to various embodiments, the multi-component tungsten film may have the following atomic percentages: W about 5% to 90%, B/Ge/Si about 5% to 60%, C/N about 5% to 80%. In some embodiments, the multi-component films have the following atomic percentages: W about 15% to about 80%; B/Ge/Si: about 15% to about 50%; and C/N about 20% to about 50%. According to various embodiments, the multi-component tungsten film is at least 50% tungsten.

According to various embodiments, the deposition is relatively high, e.g., between 400° C. and 650° C., including between 450° C. and 600° C., and in some embodiments greater than about 500° C. This facilitates tungsten chloride reduction and also permits incorporation of B, Si, or Ge into the binary film. The low end of the range is generally limited by the temperature at which the tungsten chloride compound can be reduced at reasonable reaction rates, with the temperature generally being higher than tungsten fluoride reduction. The high end of the range may be limited by thermal budget considerations. In some embodiments, any one or more of blocks 302, 306, and 308 may be performed at a different temperature than any of the other blocks. Examples of a process in which a reducing agent pulse is performed at a lower temperature than a subsequent tungsten chloride pulse are described in U.S. patent application Ser. No. 14/703,732, incorporated by reference herein. Similar temperature control may be employed in embodiments of FIG. 3A. In certain embodiments, transitioning from block 302 to block 306 and from block 306 to block 308 involves moving the substrate from one deposition station to another in a multi-station chamber. Still further, each of block 302, block 306, and block 308 may be performed in a different station of the same multi-station chamber.

In some embodiments, electrical properties such as work function of the binary or ternary film may be tuned by introducing nitrogen or carbon. Similarly, the amount of reducing agent may be modulated (by modulating dosage amount and/or pulse time) to tune the amount of B, Si, or Ge that is incorporated into the film. Still further, any one or two of blocks 302, 306 and 308 may be performed more than once per cycle to tune the relative amounts of the tungsten and the other components of the binary or ternary films and thus their physical, electrical, and chemical characteristics. Examples of different cycles for forming a ternary WBN film are described in U.S. Publication No. 20140027664, which is incorporated by reference herein. In some embodiments, the deposited tungsten-containing film has an effective work function of about 4.5-4.8 eV.

FIG. 3B shows an example of a method that may be used to fill a feature. First, a tungsten-containing multi-component layer is deposited (352). The multi-component layer may include W, one or more of B, Si, and Ge, and, optionally, one or more of C and N. Examples include WB_(x), WSi_(x), and WGe_(x), WB_(x)N_(y), WSi_(x)N_(y), WGe_(x)N_(y), WSi_(x)C_(y), WB_(x)C_(y), WGe_(x)C_(y), where x and y are greater than zero. The film may be deposited as described above with respect to FIG. 3A.

Next, the tungsten-containing multi-component layer may be exposed to a tungsten chloride precursor to deposit W metal by CVD. In contrast to block 352, the CVD-deposited W is generally pure tungsten, i.e., with no more than trace amounts of impurities. In some embodiments, the film is at least 95% W. The layer deposited in block 352 can function as a nucleation layer for the CVD W deposition in block 354. Block 354 may fill a feature on a substrate, including vertical features, such as in tungsten vias and bWLs, and horizontal features, such as VNAND wordlines. As indicated above, the methods performed with respect to FIGS. 3A and 3B generally do not include fluorine-containing precursors.

Example substrate temperatures are as low as 450° C. and may be as high as 650° C. during the CVD reaction. In certain embodiments, the tungsten chloride precursor is WCl₅ or WCl₆. In certain embodiments, the reducing agent is hydrogen gas, though other reducing agents may be used, including silanes, boranes, and germanes. In some embodiments, CVD may be implemented in various stages, such as a low temperature stage and a high temperature stage. In certain embodiments, the CVD operation may take place in multiple stages, with multiple periods of continuous and simultaneous flow of reactants separated by periods of one or more reactant flows diverted.

An inert carrier gas may be used to deliver one or more of the reactant streams in blocks 352 and 354, which may or may not be pre-mixed. In various embodiments, the precursors are introduced using argon as a carrier gas. Other carrier gases may be used as appropriate. An inert gas such as argon or another gas such as nitrogen, or a combination thereof may be provided as the background gas simultaneously with the reducing gases or the WCl₅ or WCl₆ gases. In some embodiments, the background gas flow is continuous, i.e., it is not switched on and off throughout blocks 352 and 354.

Unlike PNL or ALD processes, block 354 may generally involve introducing the reactants continuously until the desired amount is deposited. In certain embodiments, the CVD operation may take place in multiple stages, with multiple periods of continuous and simultaneous flow of reactants separated by periods of one or more diverted reactant flows. Flows may also be pulsed for a pulse time between about 1 second and about 2 seconds. In some embodiments, the reactants are continuously flowed for a time between about 400 seconds and about 600 seconds. Example ranges of chamber pressure during CVD deposition may range from about 10 Torr to about 500 Torr, or about 40 Torr.

In certain embodiments, transitioning from block 352 to block 354 involves moving the substrate from one deposition station to another in a multi-station chamber.

Apparatus

Any suitable chamber may be used to implement the disclosed embodiments. Example deposition apparatuses include various systems, e.g., ALTUS® and ALTUS® Max, available from Lam Research Corp., of Fremont, Calif., or any of a variety of other commercially available processing systems. The process can be performed on multiple deposition stations in parallel.

In some embodiments, the tungsten nucleation process is performed at a first station that is one of two, five, or even more deposition stations positioned within a single deposition chamber. In some embodiments, various steps for the nucleation process are performed at two different stations of a deposition chamber. For example, the substrate may be exposed to diborane (B₂H₆) in a first station using an individual gas supply system that creates a localized atmosphere at the substrate surface, and then the substrate may be transferred to a second station to be exposed to a precursor such as tungsten hexachloride (WCl₆) to deposit the nucleation layer. In some embodiments, the substrate may then be transferred back to the first station for a second exposure of diborane or to a third station for a third reactant exposure. Then the substrate may be transferred to the second station for exposure to WCl₆ (or other tungsten chloride) to complete tungsten nucleation and proceed with bulk tungsten deposition in the same or different station. One or more stations can then be used to perform chemical vapor deposition (CVD) as described above.

FIG. 4 is a block diagram of a processing system suitable for conducting tungsten deposition processes in accordance with embodiments of the invention. The system 400 includes a transfer module 403. The transfer module 403 provides a clean, pressurized environment to minimize the risk of contamination of substrates being processed as they are moved between the various reactor modules. Mounted on the transfer module 403 is a multi-station reactor 409 capable of performing nucleation layer deposition, which may be referred to as pulsed nucleation layer (PNL) deposition, as well as CVD deposition according to embodiments of the invention. Chamber 409 may include multiple stations 411, 413, 415, and 417 that may sequentially perform these operations. For example, chamber 409 could be configured such that stations 411 and 413 perform PNL deposition, and stations 413 and 415 perform CVD. Each deposition station may include a heated wafer pedestal and a showerhead, dispersion plate or other gas inlet.

Also mounted on the transfer module 403 may be one or more single or multi-station modules 407 capable of performing plasma or chemical (non-plasma) pre-cleans. The module may also be used for various other treatments, e.g., reducing agent soaking. The system 400 also includes one or more (in this case two) wafer source modules 401 where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 419 first removes wafers from the source modules 401 to loadlocks 421. A wafer transfer device (generally a robot arm unit) in the transfer module 403 moves the wafers from loadlocks 421 to and among the modules mounted on the transfer module 403.

In certain embodiments, a system controller 429 is employed to control process conditions during deposition. The controller will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and/or digital input/output connections, stepper motor controller boards, etc.

The controller may control all of the activities of the deposition apparatus. The system controller executes system control software including sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels if used, wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory devices associated with the controller may be employed in some embodiments.

Typically there will be a user interface associated with the controller. The user interface may include a display screen, graphical software displays of the apparatus and/or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

System control logic may be configured in any suitable way. In general, the logic can be designed or configured in hardware and/or software. The instructions for controlling the drive circuitry may be hard coded or provided as software. The instructions may be provided by “programming.” Such programming is understood to include logic of any form, including hard coded logic in digital signal processors, application-specific integrated circuits, and other devices which have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. System control software may be coded in any suitable computer readable programming language. Alternatively, the control logic may be hard coded in the controller. Applications Specific Integrated Circuits, Programmable Logic Devices (e.g., field-programmable gate arrays, or FPGAs) and the like may be used for these purposes. In the following discussion, wherever “software” or “code” is used, functionally comparable hard coded logic may be used in its place.

The computer program code for controlling the deposition and other processes in a process sequence can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program.

The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, plasma conditions such as RF power levels and the low frequency RF frequency, cooling gas pressure, and chamber wall temperature. These parameters are provided to the user in the form of a recipe, and may be entered utilizing the user interface.

Signals for monitoring the process may be provided by analog and/or digital input connections of the system controller. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be written to control operation of the chamber components necessary to carry out the inventive deposition processes. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, heater control code, and plasma control code.

A substrate positioning program may include program code for controlling chamber components that are used to load the substrate onto a pedestal or chuck and to control the spacing between the substrate and other parts of the chamber such as a gas inlet and/or target. A process gas control program may include code for controlling gas composition and flow rates and optionally for flowing gas into the chamber prior to deposition in order to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber by regulating, e.g., a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating unit that is used to heat the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas such as helium to the wafer chuck.

Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as manometers, and thermocouples located in pedestal or chuck. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain desired process conditions. The foregoing describes implementation of embodiments of the invention in a single or multi-chamber semiconductor processing tool.

The foregoing describes implementation of disclosed embodiments in a single or multi-chamber semiconductor processing tool. The apparatus and process described herein may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels, and the like. Typically, though not necessarily, such tools/processes will be used or conducted together in a common fabrication facility. Lithographic patterning of a film typically comprises some or all of the following steps, each step provided with a number of possible tools: (1) application of photoresist on a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curing of photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern into an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

CONCLUSION

Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein. 

What is claimed:
 1. A method of depositing tungsten on a substrate, the method comprising: pulsing a reducing agent, wherein the reducing agent is boron (B)-containing, silicon (Si)-containing or germanium (Ge)-containing; and pulsing a tungsten chloride precursor, wherein the tungsten chloride precursor is reduced by the reducing agent or a product thereof to form a multi-component tungsten-containing film containing one or more of B, Si, and Ge on the substrate.
 2. The method of claim 1, further comprising pulsing a third reactant to form a ternary tungsten-containing film.
 3. The method of claim 1, wherein the multi-component film is a binary film.
 4. The method of claim 1, wherein the multi-component tungsten-containing film is a diffusion barrier for a wordline.
 5. The method of claim 1, wherein the multi-component tungsten-containing film is a work function layer for a metal gate.
 6. The method of claim 1, wherein the substrate temperature during the tungsten chloride pulse is at least 400° C.
 7. The method of claim 1, wherein the temperature during the tungsten chloride pulse is at least 450° C.
 8. The method of claim 1, wherein the temperature during the tungsten chloride pulse is at least 500° C.
 9. The method of claim 1, wherein the substrate temperature during the reducing agent and tungsten chloride pulses is at least 400° C.
 10. The method of claim 1, wherein the substrate temperature during the reducing agent and tungsten chloride pulses is at least 450° C.
 11. The method of claim 1, wherein the substrate temperature during the reducing agent and tungsten chloride pulses is at least 500° C.
 12. The method of claim 1, further comprising depositing a bulk tungsten (W) layer on the multi-component tungsten-containing film.
 13. The method of claim 12, wherein the bulk W layer is deposited by a chemical vapor deposition (CVD) reaction between a tungsten chloride precursor and a reducing agent.
 14. The method of claim 12, wherein the bulk W layer is deposited directly on the multi-component tungsten-containing film without an intervening layer.
 15. The method of claim 1, wherein the multi-component tungsten-containing film is deposited directly on an insulating film.
 16. The method of claim 15, wherein the insulating film is an oxide or nitride film.
 17. The method of claim 1, wherein the method further comprises decomposition of the reducing agent to form a layer of B, Si, or Ge on the substrate.
 18. A memory structure comprising: a liner layer of a multi-component tungsten-containing film containing one or more of B, Si, and Ge; and a tungsten wordline.
 19. A memory structure comprising: a work function layer of a multi-component tungsten-containing film containing one or more of B, Si, and Ge; and a metal gate. 